Air-motor-governing device.



M. CLARK.

AIR MOTOR GOVERNING DEVICE.

APPLICATION FILED HOV. I3. I9I6.

L2Q9,56. Patented J... 12, 1917.

2 SHEETS-SHEET I.

M. CLARK.

AIR MOTOR GOVERNING DEVICE.

APPLICATION nusu NOV-13,1916.

Patente June 12, 1917.

2 SHEETS-SHEET 2. V

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UNTTED STATES PATENT @FFTQE.

LIELVILLE CLARK,

OF CHICAGO, ILLINOIS, ASSIGNOB TO MELVILLE CLARK PIANO COMPANY, A CORPORATION OF ILLINOIS.

AIR-MOTOR-GOVEBNING DEVICE.

Specification of Letters Patent.

Patented June 12, 1917.

Application filed November 13, 1916. Serial No. 130,946.

1 '0 all whom it may concern:

Be it known that I, MELVlLLE CLARK, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented new and useful Improvements in Air-Motor-Governing Devices, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof.

The purpose of this invention is to provide improved means by which any desired uniform degree of exhaust tension can be maintained in an apparatus or chamber which derives its exhaust tension from a source which is operated for producing at the same time a higher degree of exhaust tension in another apparatus or chamber, and which is in connection at the same time with both apparatuses or chambers.

It is particularly designed for governing the exhaust tension by which an exhaust air motor is operated for actuating the mechanism of a pneumatic piano player Whose pneumatic playing devices are operated by the same exhausting means.

It consists of the elements and features of construction shown and described as indicated in the claims.

In the drawings Figure l is a vertical fore-and-aft section of the exhaust mechanism and a side elevation of the, air motor of an exhaust-operated piano player equipped with this inventioh, section of the exhaust mechanism being taken at the line 11 on Fig. 3. i

Fig. 2 is a section at the line 22 on Fig. 1.

Fig. 3 is a partly sectional rear elevation of the duct-board, section being taken at the line 3-3 on Fig. 1.

Fig. 4 is a detail view of a modification of the weight device for controlling the exhaust connection for the air motor.

The usual pumpers of the exhaust means are shown at 1, 1, mounted on the rear side of duct-board, 2, which has an air channel, 3, leading respectively to both of the pumpers, from the main exhaust reservoir or bellows, 5, and from the motor-limiting bellows, 4:, check valves, 7, at the exits from the air channels serve to hold the air withdrawn against return upon reverse movement of the pumpers, as usual. The. main bellows or reservoir, 5, it will be understood, communicates through the air trunk, 53, with the partial vacuum chamber, not shown, of the pneumatic player action; and there is no restriction in the exhaust connection'between the pumpers and this main reservoir or bellows, but the pumpers can exhaust it to any degree, though a safety valve, 10, maybe provided if desired. But the degree of exhaust tension which will be maintained in this bellows by the continuous operation of the pumpers while the air is continuously admitted through the player action, is measured by the springs, 12, which tend to hold said bellows expanded, yieldingly resisting its collapse under the effort of the pumpers. The construction and operation thus far described is that which is commonly employed.

The motor-limiting bellows, 4, communicates with the air channel, 3, and thereby with the pumpers, through a port, 28, the moving wall, 4P, of said bellows, 4, carries a valve, 23, which seats at said port, 28, closing it when the bellows, 4, is collapsed. The collapse of said bellows, 4, is resisted by a spring, 25, connected to a lever arm, 26. The resistance of this spring determines and measures the degree of exhaust tension which can be produced in the bellows, 4, because as soon as the bellows is collapsed to seat the valve, 23, at the port, 28, no further exhaustion of said bellows, 4:, can take place, whatever may be the exhaust tension which is being produced and maintained by the pumpers in the bellows, 5. It will be understood that the spring, 25, is adapted to yield and permit the valve, 23, to be closed at the port, 28, upon an exhaust tension very much less than the maximum exhaust tension which the pumpers can produce in the bellows, 5. If, for example, the pumpers have a capacity for producing an exhaust tension of six ounces, which operating on the bellows, 5, may have, for example, an area of, a hundred square inches, the springs, 12, operating on the bellows, 5, will have a resistance of forty or fifty pounds; but the bellows, 4, having an area, for example, of thirty square inches, and the spring, 25, being dimensioned and tensioned to infer resistance, for example, of four pounds to the collapse of the bellows, l, an exhaust tension of about two ounces will cause the valve, 23, to be seated at the port, 28, and thereby limit the tension in said bellows, 4, to about two ounces, however much the tension in bellows, 5, may exceed that amount. I

The mo'tor-governing-bellows, 6, communicates with the motor-limiting bellows, 4, through a duct, 8, leading from a port, 13, of said governing bellows, 6; to a port, 11, of the bellows, 4, and with the air motor, 20, through a' port, 18, leading to a pocket, 19, in the duct board, into which pocket the air trunk pipe, 22, is connected, said air trunk leading to the motor. The moving wall, 6 of said bellows, 6, carries a valve, 14, which seats at the port, 13, closing it when the bellows is collapsed. The collapse of the bellows, 6, is resisted by a weight, 15,

which may be carried in a variety of ways with said moving wall of the bellows, 6, for affording such resistance. When said governing bellows is in approximately ver-.

tical position as shown in Fig. l, a convenient method of mounting the weight is that illustrated in that figure, consisting in providing a lever arm, 16, extending off from the hinged end of said moving wall, on which lever arm the weight, 15., is hung. or otherwise mounted, the lever arm being preferably notched to afford graduations and means of positioning the weight on the lever arm according'to the tension to. which the motor is to be governed. An equally eiiicient means consists in connecting the free end of the moving wall, 6, by a cord, l7,.passing over a pulley, 1.9,] mounted in any'convenient place on the structure, and carrying the weight suspended, as illustrated in Fig. 4. I p

The exhaust tension at which the spring, 25, is calculated to permit. the collapse of the bellows, 4, is somewhat lower than the minimum tension adequate for the softestplaying, but suiiiciently. high for the operation of the motor at the maximum speed. Since this tension in the bellows, 4, will be practically'uniform, varying: probably only a few ounces in the total pull on the spring, 25,. at the instant of change of the valve, 23

from open to closed. or closed to open position, the. tension to which the governor bel lows, 6, can be exposed when the valve, 14,.

is open at the port, 13, is substantially uniform, and in any event, whatever he the tension in said bellows, 4, no higher degree of exhaust tension can be produced in the governor bellows, 6,, than is sufficient to collapse that bellows against resistance of the weight, 15. which is uniform for any position to which the weight may be adjusted on the lever arm, 16; andthe speed of the air motor, 20, which is represented conventionally by the bellows and connections seen in elevation in- Fig, 1, connectedfor operation. by the trunk, 22, will therefore be the same, however the pumping is.

varied for varying the loudnessof the plaving by the pneumatic playing devices, not

the main bellows, 5.

shown, which derive their energy through The reason for interposing the limiting bellows, 4, between the exhaust devices and the governing bellows, 6, that is, if the governing bellows were connected directly in the position of the limiting bellows, 4, while the exhaust tension in said governing bellows would be practically uniform, the total pressure for collapsing said bellows varying only by an ounce or a fraction of an ounce at the instant of open ing and closing of the valve, 14, yet in the instant during which the valve is open, the air will be drawn through the governing bellows from the motor at a rate which would vary according to the exhaust tension in the main bellows, 5, which variation might be from two ounces to six ounces; and during that instant therefore, the speed of the motor might be appreciably varied according to whether the exhaust tension in the bellows, 5, was being maintained for loud playing or soft playing; that is to say, the motor would speed up for a second during loud= playing, though it would not be thus affected during soft playing, and thus in the absence of the limiting bellows, 4, the. governing bellows, 6, would not in sure perfect uniformity of action of the motor, as is necessary in order that the tempo may be controlled absolutely by the tempo-governing devices.

It willbe understood that the usual means of varying the speed of the air motor according to the desired tempo of the music played, is provided in the form of a valve, 21, controlling the air inlet from the motor. When the cord-and-pulley-suspended weight shown in Fig. 4 is employed for resisting thecollapse of the motor-governing bellows, the tension limit of the governor will be varied by adding or removing weight disks, the weight being'made up of aplurality of such disks, asindicated in the illustration of the same in Fig. 4.

1. In an automatic playing mechanism, an air motor governing device comprising in combination with an exhaust means, a collapsible chamber having an exhaust port through which it communicates with the exhaust means avalve operated by the collapse of the chamber for seating at the exhaust port; means yieldingly resisting the collapse of the chamber; a second collapsiblechamber havingan exhaust port'through which it communicates with the first 001-,

lapsible chamber; a valve operated by the an air motor governing device comprising in combination with an exhaust means, a collapsible chamber having an exhaust port through Which it communicates with the exhaust means; a valve operated by the collapse of the chamber for seating at the exhaust port; means yieldingly resisting the collapse of the chamber; a second collapsible chamber having an exhaust port through which it communicates With the first collapsible member; a valve operated by the collapse of said second chamber for seating at said last mentioned exhaust port; Weightoperated means yieldingly resisting the collapse of said second collapsible chamber, and an exhaust connection from said last mentioned collapsible chamber to the air motor.

In testimony whereof I have hereunto set my hand at Chicago, Illinois, this 8th day of November, 1916.

MELVILLE CLARK.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

